The invention relates to a double progressive spectacle lens having a prefabricated progressive surface and a second progressive surface for correcting a spherical ametropia or a cylindrical ametropia.
Conventional spectacle lenses are known from the prior art. They are distinguished in that there is a limited number of progressive surfaces, so-called base curves, with the aid of which the complete active zone consisting of sphere, cylinder, axis and addition is covered. The adaptation to the individual action is then accomplished by a prescription surface that is spherical or aspheric, toric or atoric. This has the disadvantage that such a progressive lens has optimum properties only for the middle of the base curve and this also holds, in particular, for the addition. If an individually atoric surface is applied to the rear side, it is also possible to improve the properties outside the central zones of the prior art.
Also known from the prior art are progressive lenses from Rodenstock, which have been produced by means of the so-called individual lens technology (ILT), that is to say by taking account of customer-specific parameters such as pupil distance, corneal vertex distance, frame forward tilt and frame disc angle. Reference is made in this regard to U.S. Pat. No. 6,848,788 (=WO 01/81985); US 2004/017543 (=WO 01/81981); U.S. Pat. No. 6,669,337 (=WO 01/81982) and U.S. Pat. No. 6,832,834 (=WO 01/81979), for example.
Asymmetric surfaces are described in U.S. Pat. No. 6,074,061 of Tokai and also outlined as prior art, although the iso-astigmatic lines in the progression channel and in the near zone run virtually parallel to the principal lime. Also, the astigmatism in the position of use has a similar structure to surface astigmatism.
U.S. Pat. No. 6,213,603 (=WO 98/01787) describes a progressive spectacle lens in which the magnitude of the surface astigmatism of at least one of the surfaces contributing to a change in power has, along at least one section of the spectacle lens with a horizontal plane, a local maximum that is at a distance of not more than 4 mm from the principal lime and at least one local minimum that does not lie on the principal lime and whose distance from the principal lime is greater than that of the local maximum.
The documents cited here as background information refer to single progressive spectacle lenses.